A comparative study of the 'Air gap' technique and the 'Grid' technique in digital radiography of lateral hip shoot through.

Abstract

Introduction In the local hospital the lateral hip standard projection using a horizontal beam is performed using a grid as an anti scatter technique. However, other studies have shown that using an air gap technique instead of the grid would increase image quality as well as reduce the radiation dose given to the patient. This study compares these techniques using a quality control phantom and an anthropomorphic phantom to determine which technique provides the best image quality in the aforementioned projection. The aim of the study was to establish whether the air gap technique produces images of higher diagnostic quality than the grid technique whilst identifying which technique was able to most effectively reduce scatter radiation reaching the detector and if the air gap technique is more suitable to project the hip laterally than the grid technique. Methodology In this quantitative, quasi-experimental research, image quality of radiographs taken using the two different anti-scatter techniques was tested using a quality control phantom to assess for spatial resolution and contrast resolution. The image quality of both techniques was compared. The dose area product of each exposure made was also recorded and compared as an indication to the researcher of the radiation dose that the patient would be exposed to. A Likert Scale was also performed on the images acquired after irradiating the anthropomorphic phantom. This was done by randomly selecting two radiologists to report on the images. Results Results obtained demonstrate that there was a significant difference in the image quality between the air gap and grid technique. The signal to noise ratio was also increased in the air gap technique exposures due to more signal having been recorded in comparison with the grid technique. The Likert Scale also showed that the radiologists were most confident reporting on the 30 cm air gap exposure rather than the grid technique exposure. The DAP readings of the grid technique and an air gap exposure with an OlD of 30 cm were the same. However, the radiologists felt more confident to report the 30 cm air gap technique rather than the grid technique. The results recorded for both techniques were compared and analysed. Conclusion From these results the researcher presented his conclusion and recommendations that may help to improve a similar study by also comparing patient doses in the grid and air gap technique